On Wed, Aug 13, 2025 at 10:42:50AM +0800, Zhang Yi wrote: > From: Zhang Yi <yi.zhang@xxxxxxxxxx> > > The Linux kernel (since version 6.17) supports FALLOC_FL_WRITE_ZEROES in > fallocate(2). Add support for FALLOC_FL_WRITE_ZEROES support to the > fallocate utility by introducing a new 'fwzero' command in the xfs_io > tool. > > Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=278c7d9b5e0c > Signed-off-by: Zhang Yi <yi.zhang@xxxxxxxxxx> > --- > v1->v2: > - Minor description modification to align with the kernel. > > io/prealloc.c | 36 ++++++++++++++++++++++++++++++++++++ > man/man8/xfs_io.8 | 6 ++++++ > 2 files changed, 42 insertions(+) > > diff --git a/io/prealloc.c b/io/prealloc.c > index 8e968c9f..9a64bf53 100644 > --- a/io/prealloc.c > +++ b/io/prealloc.c > @@ -30,6 +30,10 @@ > #define FALLOC_FL_UNSHARE_RANGE 0x40 > #endif > > +#ifndef FALLOC_FL_WRITE_ZEROES > +#define FALLOC_FL_WRITE_ZEROES 0x80 > +#endif > + > static cmdinfo_t allocsp_cmd; > static cmdinfo_t freesp_cmd; > static cmdinfo_t resvsp_cmd; > @@ -41,6 +45,7 @@ static cmdinfo_t fcollapse_cmd; > static cmdinfo_t finsert_cmd; > static cmdinfo_t fzero_cmd; > static cmdinfo_t funshare_cmd; > +static cmdinfo_t fwzero_cmd; > > static int > offset_length( > @@ -377,6 +382,27 @@ funshare_f( > return 0; > } > > +static int > +fwzero_f( > + int argc, > + char **argv) > +{ > + xfs_flock64_t segment; > + int mode = FALLOC_FL_WRITE_ZEROES; Shouldn't this take a -k to add FALLOC_FL_KEEP_SIZE like fzero? (The code otherwise looks fine to me) --D > + > + if (!offset_length(argv[1], argv[2], &segment)) { > + exitcode = 1; > + return 0; > + } > + > + if (fallocate(file->fd, mode, segment.l_start, segment.l_len)) { > + perror("fallocate"); > + exitcode = 1; > + return 0; > + } > + return 0; > +} > + > void > prealloc_init(void) > { > @@ -489,4 +515,14 @@ prealloc_init(void) > funshare_cmd.oneline = > _("unshares shared blocks within the range"); > add_command(&funshare_cmd); > + > + fwzero_cmd.name = "fwzero"; > + fwzero_cmd.cfunc = fwzero_f; > + fwzero_cmd.argmin = 2; > + fwzero_cmd.argmax = 2; > + fwzero_cmd.flags = CMD_NOMAP_OK | CMD_FOREIGN_OK; > + fwzero_cmd.args = _("off len"); > + fwzero_cmd.oneline = > + _("zeroes space and eliminates holes by allocating and submitting write zeroes"); > + add_command(&fwzero_cmd); > } > diff --git a/man/man8/xfs_io.8 b/man/man8/xfs_io.8 > index b0dcfdb7..0a673322 100644 > --- a/man/man8/xfs_io.8 > +++ b/man/man8/xfs_io.8 > @@ -550,6 +550,12 @@ With the > .B -k > option, use the FALLOC_FL_KEEP_SIZE flag as well. > .TP > +.BI fwzero " offset length" > +Call fallocate with FALLOC_FL_WRITE_ZEROES flag as described in the > +.BR fallocate (2) > +manual page to allocate and zero blocks within the range by submitting write > +zeroes. > +.TP > .BI zero " offset length" > Call xfsctl with > .B XFS_IOC_ZERO_RANGE > -- > 2.39.2 > >
